Me and my mate decided to start a post hardcore band (alexisonfire, thrice, fightstar ect) not really sure what gear to get. about 250 pound budget.
currently have some really old "kustom" amp. it isn't terrible. has okay cleans but distortion isn't perfect.
what pedals should i get if i stay with this amp?
what amp should i get?
i know it's preference but i'm thinking what suits the style.
Trade the amp, or sell it outright. I can say that right away, you will not get the sound you want if the cleans are only okay and the distortion is smeh. Go to a shop. Try out different guitars, try out different amps. No one can tell you what to buy to sound the way you want to sound, of they say differently they are full of shit.

I have played in a few Post Hardcore bands, once with a Strat with texas specials through a peavey ultra 410. Now I play an sg and a ibanez jet king 1 through a peavey ultra tube. Those have sounded the best to my ear by far. And these are not expensive items.