Hi Zard.
Welcome to the forum. If you are not going to measure mains voltage, then almost anything will do.
The Aneng dmms are popular, been meaning to get one myself.
UniT brand is variable, some models are good but some are bad. The UT61e as mentioned is good value considering its resolution but again not considered safe for live mains (especially if it has been modified). The UT139 is considered safe for mains.
Brymen is a good brand if you can find them
If you get used from ebay, any Fluke is good but you will find it hard to get one for £50.
Why are some dmms not safe for mains? Dmms now have a rating called CAT, this rating tells you to what voltage and indirectly power the dmm will protect the user if there is a power surge. Power surges can blow components in the dmm and the blast can injure you, see Dave's video where he blows up dmms.
Hope this helps.