Recommendation for engine rebuild in the Glasgow location?

Per title folks, can anyone recommend a good reputable engine builder in the Glasgow location. The car is running a bit rough and after doing a compression test one cylinder has really low pressure. I suspect this is going to be a sticky valve (put some miles on her but hasn't come unstuck) or worn rings so looking for an honest diagnosis of the problem and what needs doing to fix.

Anyone got any idea of rough cost for a rebuild on a 1.6 nowadays?

Cheers,

Have you tried compression testing it with a squirt of oil in the bores? If this bumps compression, you can rule out a sticky valve. Alternatively you could do a leakdown test, which can highlight several issues.