Camelot difficulty spike: Advice for a newbie

For starters, if you are having trouble on the first node you should use the current event to max some servants, sieg and robin will help you on some bosses so having them maxed will make it easier, with max lancelot+mash+waver supp you should be able to push trough most stages with ease, i used herc with mash and waver to push trough most of the non boss nodes by keeping herc alive to do the damage, also using the guide will help you decide how to better prepare for each stage.

https://grandorder.gamepress.gg/camelot-spoiler-free-walkthrough

There is a huge spike.

Your best bet now is to focus on leveling up your units via the daily quest. Your Ozzy needs to be 80 minimum (really should be 90).

Cu Chulainn needs to be up at 70 minimum.

Hans, 65? He just needs as much HP as possible.

Lancelot Beserker as well.

You just need to focus on leveling and ascending and taking MAX advantage while the 1/2 AP is in play. Where your units are at they will wipe everytime. You think its hard now at the first few nodes, you are in for some real BS in this Singularity.

These units under level 70 will not be helpful unless they are support. Your damage dealers won't hit anywhere near what they need to at those levels.

Focus on Ascending and leveling up. Your best chance.

Trust me, this singularity has some BS lined up...

I would level your initial line up to max first. Your main damage dealer will definitely be Ozy. You lucked out with him he's a fantastic servant. Back him up with a crit generator and a support. So Hans for sure and either Hassan or Fuuma. Have a tank in the back to take NP hits, I recommend either Leonidas or Mash to go with Ozy. Or David for party wide Evade. It depends on the enemy servant. When in doubt, Mash is the safer choice. The last slot is your choice. Back up support or star gen or what I like to call a brawler servant. This is your last stand servant that functions best when alone and is hard to kill. Heracles and Nero are prime examples but the cheaper version is vanilla cu.

Edit: I forgot to mention you will need a substitute damage dealer for Ozy in some stages of Camelot. There are a lot of assassins. Unfortunately theres not a great selection of casters to choose from. Medea is ok, but there's a certain, rather difficult stage where an aoe caster is better. Or an aoe berserker. You do have Lancelot. Its just hard to keep a berserker alive.

First off, how did you even get through the America singularity with those servants?? You really need to lvl your servants up if you want to even try Camelot. Max out their lvl and try to work on their skills a bit before you try Camelot again cuz its really gonna start kicking your ass midway even if you have maxed servants.

To add to what the others have said:
I'm also generally an f2p player and have been playing since the Accel zero event (I did spend $30 on the anniversary summon because a guaranteed SSR seems like a good buy to me).
First things first, Camelot is completely a breeze even with the gimmicks with a full team of level 70-90. I believe the intended difficulty is for it to be beaten by strategic level 60 teams with level 70 being the point where it isn't reliant on crit rng so much.
Generally the best way to get a team up to speed in my opinion would be to focus on Ascension first till you have at least a max ascended servant in every class possible. The extra health and atk from being max ascended vs not is huge even for supports (though of course it is bigger impact for dps). To get max ascended, really take advantage of event shops and events like the current one to collect mats.
Consider the current event, probably the best time in the year to farm both exp tokens as well as class pieces and monuments. The next event (I think it's the swimsuit one yay!) will have an event store again I think, so focus then on collecting Ascension materials.
Basically what I'm saying is think of the main story as something that needs to be accomplished long term rather than as soon as possible. My personal prep for Camelot happened during the onigashima event where I heavily invested in max ascending a lot of servants (tip for you: Euryale is absolute bae on Gawain)

First level whatever you are working on to 3rd ascension at least. Max out cu david and kotaro. Then level medea shakespeare lubu babbage hundred persona arash kogil in that order. Feel free to skip ones you don't want. Only then should you worry about team comps.

Agreed with the consensus here, level your servants first. This is extremely important. I started about 2 months ago and have almost exactly the same battle strategy as you, just getting the strongest servants with a class advantage and going HAM. Has worked very well for me so far and Camelot was no different, other than a few gimmicky boss fights, and even those weren't really a problem after you know what you're getting into. All you really need is to get your servants as close to max level as possible and you should be fine. Instead of levelling weaker servants or servants you aren't really planning to use, I would recommend saving those embers for the ones that you will be using frequently.

Definitely leveling and ascension. Camelot makes America look like a joke in comparison. Pick your support member wisely for each battle because the enemies in this Singularity will make you dearly regret not doing so- the bosses especially.

And seriously, watch out for Gawain. No spoilers but of all of the bosses, he’s the one I found most unpleasant.