As someone who checked out one of the Neotecs that postcardcv mentioned, after a good look ended up with an 055.
I think the key thing to look for is a tripod at least as stable as the Manfrotto 055 you mention, and it should have a centre column that can be set to the horizontal position. Current workshop project is to do this for my version of the 055 that does not feature this.
I have several tripods including the original Benbo that nirofo mentions. In my opinion they offer a more rugged design and greater stabilty at odd angles than the 055, but they are a quite different design having a single locking clamp, and although brilliant, some people struggle with them. So I would say you really need to see one and have a little play to see if it suits you personally.
There are also lots of tripods of dare I say it more conventional design and there you should look for leg movements at least similar to the 055 you saw, plus the ability to set the centre column to horizontal. Unless weight is an issue then there is little need to go for carbon fibre.
Next up may be the head as you are moving from the Jessops tripod, and for that you would probably be best taking your camera and lens with you to the shop and trying one out on a demo tripod. Head choice is a personal thing so my feeling is that recommendations can really only be of value if it is type specific, and weight is given to the available budget.
Ballheads are very flexible in their movements but ideally should have some degree of friction control to stop the ball with camera mounted falling when the lock is released (scary). Ball heads tend to be more expensive than pan and tilt for a given load capacity due manufacturing costs, and some have quite statospheric prices. Andys collection from a previous thread springs to mind.
Pan & tilt are cheaper to manufacture and come in a fair variety of styles so its personal choice.
Probably the best I can say for either ball or pan & tilt is to check the rated load capacity, then check out ones that faily well exceed the weight of the kit you intend to use on it.
To example that among my collection I have pan & tilt Manfrotto 460MG head rated at 3kg capacity. This is fine for my D100 and lens at 1.3kg but definately deflects under the load of my D2X and lens at 1.5kg. So although it is capable of carrying the load, I find it less than satisfactory for the D2X for which I use the bulkier Manfrotto 808RC4 rated at 8kg.
Don