That's a very open ended question.
What sort of touring setup are you thinking of? Are you going classic five bag bike touring? or the more modern ultra light bikepacking?
Are you planning to cook at your tent, or eat in pubs/chippies etc... along the way? If so you'll want a stove. If you want a stove, Kim will be along shortly to recommend a trangia. I'll throw in a proper multifuel stove like the MSR whisperlite Internationale, and someone else will say esbit. (Find the stove threads in camping it up to see all the arguments why they are all wrong).
If you're not fussed about speed, and want some camp comfort, a light weight chair can make life more comfortable. (again, see threads in the camping it up section).
Don't forget stuff to maintain your bike, (lube, spares, tools), but also to maintain you (saddle sore cream, first aid kit etc...).
Good luck!
J