Here's a link to JIB rates
http://www.jib.org.uk/ops0507.htm
and here's a quick cut and paste from the above URL
Grade Transport Provided Own Transport
Technician (or equivalent specialist grade) £15.10 £15.86
Approved Electrician (or equivalen grade) £13.33 £14.09
Electrician (or equivalent specialist grade) £12.22 £12.99
Electrical Improver £11.00 £11.69
Labourer £9.70 £10.42
Senior Graded Electrical Trainee £11.00 £11.69
Adult Trainee £9.70 £10.42
Adult Trainee (under 21) £7.28 £7.82
JIB are employed rates, so I'd add extra (50%) to the rate for s/employed worker requiring:-
Own transport
Stores / office
holidays
professional development / training
insurance
tools and test kit
vat / tax and NI
Like everything, it depends where your patch is, local market dectates rate more than a JIB table.
London rates, as with any high demand area with guys that are always busy will realise a premium.
It also varies a bit with hour, day or weekly rates. A rewire tends to work out cheaper than doing 5-10 different jobs a week.
The biggest single issue is a mix between how good you are and what the local market pays.
Try getting the wife to phone up some sparks and get verbal quotes for fixed jobs.