Who taught you radio communications?
Could be quite simple:
"Liverpool Ground, G-XYZZ, Good morning"
"Go ahead"
" G-XYZZ, C152, Pos GAT, VFR local, request sightseeing my home at St Helens, request low height CTR, Information XXX aboard, request taxi"
...
"Liverpool Tower, G-XYZZ, Pos A for RWY XY, ready for departure"
"After TakeOff left/right turn approved, cleared for local sightseeing, max. 1.200ft, stay outside direct VFR routes, report when leaving CTR, have a nice flight, cleared for take off RWY XY"
It's no rocket science and this is similar to what I do in these cases. If you go for a low traffic time it should be no problem and if in doubt when - simply call tower by phone in advance to ask. It's ordinary people anywhere ;-).