Crikey, where do I start? I would say that most of the VS stuff done with BRT is with CV's, however if your trying this for the first time you don't really want to be looking at very faint stars at minimum or empty sky if they are too faint for even the C14. Have a look at the BAAVSS web pages (which I look after) www.britastro.org/vss/
or the AAVSO web site www.aavso.org
and here you will see lots of information and lists of stars to observe. Look at the range of the stars brightness (it's amplitude), check at what brightness it is now as this will dictate your exposure, and what type of variable it is. For anything other than a CV I would use a V filter, as any red star (Mira, SR etc.) will appear at least two-three magnitudes brighter if you don't use a V filter. If it's a bright variable, or a Mira which is near it's maximum brightness, think about ClusterCam, as this will give you a larger field and more choice of comparison stars.
A really nice Mira star to follow is SS Her. It has a short period (107d) and an amplitude of 9.0-13.0. A 20000 exposure with a V filter should be OK on this. Keep with it throughout the observing season and you will get a nice plot at the end of it.
Do you own any binoculars or a telescope? Why not try a spot of visual astronomy with a variable star if your conditions allow? Much more fun than CCD's!
If you want more info. on this, drop me an e-mail off-forum and we can discuss further.