Coaches don't work out so well but there are options with National Express.
Please confirm and book your return tickets rather than having open returns

Evening departures which allow decent time at Gear are:

Service	Destination	Time
040	London *	2000
336	Birmingham / Wolverhampton / Manchester	2000
202	Newport / Cardiff / Bridgend-Sarn / Port Talbot / Swansea	2010
040	London *	2100
040	Weston-super-Mare / Burnham-on-Sea	2100
201	Chepstow / Newport / Cardiff / Bridgend-Sarn / Port Talbot / Swansea	2325
	* many connections are available from Victoria Coach Station