UKC

I'm planning a trip to hike Snowdon, and naturally want to get in a few days of climbing while I'm there.

Best bouldering and sport crags there? (unfortuntely I don't have a trad rack).

Best bet would be slate quarries in Llanberis or A55 crags for sport, can't help with bouldering.... my dad told me not to talk to boulderers !!

Lots of bouldering in the Llanberis pass, right at the foot of Snowdon. See:

Cromlech boulders

Sport is more difficult - no bolted routes in the mountains themselves - as above the Llanberis area slate quarries are the nearest : 

Australia

Bus Stop Quarry

Twll Mawr

Lots more of both dotted around the same areas if you look at the maps. 

Otherwise you need to head out to the North coast (Great Orme) for limestone sport routes and bouldering

Pen Trwyn#maps

Parisella's Cave#maps

Or to the Llangollen area. 

If you can beg, borrow or steal a simple rack it would open up way more options.