New central heating system (northwest)

Anyone know if this quote is reasonable?
We're in a 2 bed 60s bungalow with old storage heaters only. Applied for gas supply.
Found someone online with many good reviews who says he'll supply and fit:
A rated Baxi combi boiler with 7 yr warranty
programmable room thermostat
4 radiators, 1 towel radiator
all associated pipework (plastic)
removal of existing tank and hot water cylinder
removal of storage heaters
£3750 inc VAT
We've had another say copper pipes are best (no chance of leaks) while this one says plastic pipes are more efficient (lose less heat).
Also, would you advise installing a small radiator in both a very small porch and small internal hall?
Any advice appreciated.