I collected like 10k trout whats a good spot to cook them all?

Many players train firemaking in GE, it's very rare that there are no fires. So it could do. Or Lumby Castle.

Closest range to a bank is in edge.

Al Kharid is great if you never want to open gates and doors or set your own fires. That's what I used when I was f2p.

Persoanlly what i did was got to karamja and fish and cook and bank fish cook bank =p

Just go GE, always there is someone training fm...just use his fire :

Edgeville :) very close to a bank

there is a range just west of the bank in eastern falador, its what i use when cooking fish on my pure

Make a fire outside edge bank and cook. It's a peaceful place. That's what I did when I went for 99 cook in f2p.