Antoni,
This depends on many things, for instance:
How big is the water you are going to fish (how far do you need to cast).
How big are the fish.
What type of action and test curve the rod has.
What method you are going to use (this also effects the breaking strain of line you use).
I would recomend you have a look at the Okuma Epix Baitfeeder range as these reels have 10 ball bearings which will make the retrieval of rigs and playing fish smoother and less stressfull on the reel, as the name sujests it also has a free spool facility so you can fish bolt rigs without the rod being dragged in and they come in a good range of sizes all for ?59.95 each.
There are also the more common Shimano and Daiwa reels but they can be more expensive.
Hope this helps.