Coventry
First, welcome to the Forum. Regarding recruitment prior to and during the Boer War, it must be realised that the Cardwell Short Service scheme (introduced in the 1870's) provided for men to serve six years with the colours and six in the reserve. As a variation, I have seen examples where men served five and seven in the 1890s. Prior to Cardwell, men enlisted for twelve years full time. The new scheme eventually provided a large pool of reservists; liable to be called up. Some might have been a bit unwilling and reservists would have needed refresher training and the like - but they were used to arms and discipline.
The subject of recruitment for the British Army in the late 19th Century is an interesting and wide ranging one and might I suggest you look for a copy of "The Late Victorian Army, 1868-1902" by Edward M.Spiers ISBN 0 7190 2659 8. If not available via booksellers, your local library might assist.
Keep us posted with your research about the Royal Warwickshire Regt. Do you have any Boer War medals to that unit to share with us?
Regards
IL.