Hi Andy
You don't have to cross the waters to see stunning rock art, You've got a shedload of it. I'm sure Mr FW can point you in the right direction.
I guess FW's and Anthony Weirs sites are a good places to check out your native rock art.
If you are tempted to come over to Blighty I'm sure you'll find folk on here who'll be more than happy to give you a tour around some of the carvings.
You would be more than welcome to attend our 2007 rock art meet-up which will be held in Dumfries and Galloway, we'll be in the neighbourhood of Stranraer, handy for the ferry.
The Rock art in the British Landscape website is a good starting point
http://groups.msn.com/rockartinthebritishlandscape
You'll find some good titles here
http://groups.msn.com/rockartinthebritishlandscape /bibliography.msnw
The Bradley's book looks at the Atlantic Coast of western Europe whereas Beckensalls British Prehistoric Rock Art takes-in mainland Britain.
I've not read this book but I've heard it's a bit tasty. Tasty price too!
http://www.amazon.co.uk/gp/product/0198131933/sr=8-7/qid=1154704586/ref=sr_1_7/202-8318685-0031868?ie=UTF8&s=gateway
cheers
fitz