£125pp spread betting on the FTSE 100 on a £5000 account is frankly ridiculous.
Consider this, I am working on a trading plan to allocate 0.5% of total capital to each trade, for example £2 pp with a stop at 25 points below. This is off total capital of £10,000.
I know of some other traders who use a similar system and only bet at £2-5 pp. I may only make 20% a year (1.8% a month), 30-35% if I get really good, but at the same time the risk of blowing the account is greatly reduced