I have been to two chrome platers this week and they both said I would be best going to Midland Chrome Plating. They said they could do the nickel fine but the chrome could leave shadowing because of the nature of the frame (Aero Reflex, twin/triple tubes) and their tanks. Johnnyt72 on raleighburner.com suggested Prestige electroplaters at mexbrough, 01709577004. There is a long turn around apparently but they will tell you the details.
I was quoted £35 for bars at Castleford Chrome Platers. The same price for a crank and chain ring.
Simon.