Don't know if this one is any help
Plumbsure Flexible Tap Connector (L)500mm
Product code:03890172
http://www.diy.com/departments/plumbsure-flexible-tap-connector-l500mm/195905_BQ.prd
Or 500mm search results
http://www.diy.com/search/results/c...=500mm&pageSize=12&categoryToFilter=DIY768242
If you're not comfortable with copper soldering just use some push fits and extend the 15mm pipe. Keep flexi tails as short as possible.