Greenwich - Tarantulas are easy to care for. Go for a brachypelma or grammastola type. They're easiest. Mine that died was a brachypelma smithi (mexican red knee, black and orange ones often used in films, james bond had one in). The females can be pricey though (£60 - £100).
Grammastola rosea (chillean rose) are another easy to care for T. They're very cheap - I've never paid more than £15 for one and not too skittish (generally, the less skittish live longer).
I don't bother with heat mats because my house is ridiculously warm, where we lived before they all had heat mats, just bog standard ones that cost a tenner, or little red heat lamps, £2 or so from wilkos.
They eat crickets or locusts once or twice a week. Some eat much less though.
Females live longer. A male dies after it matures. If you buy an adult male it will be dead before a year. 18 months tops. Females can reach 20/30 years.
My red knee was 12 :) her moult went wrong which is why she died.
We've only had three escape (out of over 120 between me and my mum!). Two were let out by cats. One was our own fault - we thought the 9 inch bird eater wouldn't fit through a small fitting hole. We were wrong.
Snakes, I'm not a fan of. They are better at escaping. Especially small ones. We've had them go missing for months, and turn up in all sorts of places - in drawers, in the shed, in the blinds, under the sofa. They are also more costly equipment wise what with heat and lamps etc.