On the hot side, better to tee off the pipe in the loft, rather than in the airing cupboard with an inverted U.I know I will have to fit a pump, just thought there may be something I could do at the water cylinder end to maybe help. Plus, not sure where the pump would go. Probably in the airing cupboard, but just means pipes would be coming down from the loft to go back up again
Are you sure it's the best shower head for low pressure? Maybe a replacement would give more flow. I have a gravity fed shower, about 1.3m between shower head and CWST water level. It won't take your skin off, but it gives a perfectly acceptable shower.