Horses for courses. Depends whether you a rich man or not (I'm guessing with your £40 budget that like most of us you're not a lottery winner) and whether or not it's for a bit of home use prodding and poking, or if it's for your job and your everyday bread and butter depended on it. I'm a software engineer so my laptop is my job. I have an HP with Intel CORE vPRo i7, Intel Pro 2500 Series SSD, 8GB DDR3-1600 RAM, 64-bit OS, etc., with enterprise level support/warranty. It cost my company a lot of money. I couldn't do my job on £299 laptop from PC WORLD
But playing with electronics (model railways, Arduino and pinball) is my hobby so I can get away with something modest. My first job after leaving uni was working in Maplin (loved it, great job!) and we used to sell a lot of multi-meters. We had them all from a little pocket analogue jobbie for a fiver up to the full range of Fluke meters. Back then I bought myself a
Precision Gold PG 012 and it's done a great job. Perfectly usable for checking a connection in your wiring loom, or testing voltages on the transformer, or coil diodes, or lamp/solenoid driver transistors, etc. It's still available for £34.99. Tests continuity with a buzzer, reads DC and AC voltages up 600V, resistances up to 2000M, capacitance to 20uF, frequency to 15MHz, diode test and NPN/PNP transistor gain.
But I've noticed that the higher specified
PG 017 model is actually cheaper, currently on offer half price at £19.99! This adds current testing up to 10A.
I did however "treat" myself to a
WG 020 last month as it was (and still is) on offer for £14.99. This adds capacitance up 200uF, DC up to 1000V, AC to 750V, inductance to 20H and duty cycle. It's bigger than my PG 012 but comes in a rubber case (they used to be sold separately).
I'm sure others will be appalled at my recommendation of Maplin multi-meters, but they've been good for me, worked flawlessly and if there any problems you've got a real shop to take it back to.