Yes is the answer, if mains pressure is ok then leave it in 15mm and fit a 15mm to 3/4 adapter or a 15mm to 3/4 flexi tap connector is the simplest way!
RAWPLUMB
February 2010
I can answer this question...
Can I spur from a 15mm cold feed-pipe upto a 22mm pipe to supply my bath ta?
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix plumbing.