It's a high pressure (mains) system but not a combi - it uses a wonderful pressurised hot water tank in the airing cupboard so that both the hot and cold feed are perfectly balanced and pressure / flow is superb. Showers are so great that I find hotels underwhelming on that front!
I am agile but don't have three hands and there's very little space to crawl underneath.
TBH, I am not looking forward to the installation itself, never do where taps are concerned as they almost always present the same challenge. But a combination of patience, brain and the right tools usually works and I have previously installed a whole bathroom suite so this one shouldn't be too onerous. I'm off to check that link you guys provided to Screwfix.
But any further suggestions are welcome. And yes, I will be turning the stopcock off and draining the tank first Crockers
Arianne