In reply to jussy:
If you only have a couple of hours, you might be better sticking to the shorter Holyhead mountain routes. You would need to be bloody efficient to manage anything else, even single pitch routes (the Strand e.g.)on the upper tier.
Depending on the sort of climbing you like, King Bee crack is a good honest HVS struggle or there is a *** E1 (who's name escapes me) which is pretty amenable steep slab climbing - both on Holyhead mountain.