If your husband is enough of a hard-core biker then 8-10 miles is nothing.
DW knew a fellow student in Stoke who biked about 30-40 miles to Stafford for his placement work and loved it.
8-10 miles should be doable, but of course, will he want to do it when he gets really cold or pisses down with rain?
People in the UK cycle along 60 or even 70 MPH roads with no cycle lanes so again it's all down to his inclination. Of course, having a good cycle route there would help, I'm sure.
In regards to train tickets, once you get outside of London Underground area, rail fares go up quite a bit more, especially going into London. High Wycombe station near us charges something like £14-15 off peak for a travelcard return to Central London. Meanwhile, just down the road in Amersham which is on the end of the Metropolitan line and is only a few minutes faster to Central London it is only about £7 off peak, so close to half the price. Buses are the same way, the Mayor of London has subsidized bus routes and train routes while the Home Counties often charge much more because they haven't got the same subsidizing funds or they just don't have the inclination to do it.
Matt