You can save, or waste, plenty of money by your choices regarding buying foreign currency. I recommend checking out the links below from the Telegraph, and also using travelmoneymax.com (from Money Saving Expert) to work out exactly how much it will cost you to order a certain amount of foreign currency.
Sadly, mum banks with Barclays, and her card charges a fee each time she withdraws money abroad. The best option is the specialist Halifax card, which my mum can’t get because of a bad credit rating. I’m not sure if mum trusted the other sources for either collection or delivery of her money, as she’s going to the Post Office instead, which offers mediocre rates. But I’m including the links here so that it might help other people.
Worst banks for withdrawing cash abroad (Telegraph)
Essential travel money checklist (Telegraph)
I haven’t bothered shopping around for a SIM card for mum, as Amaysim was the one that came up best when I moved here and the rates are still competitive. With 25c for each text and 16c/min for calls to a UK mobile, it hardly seems worth checking any other providers. I just need to decide whether to lend her one of the boys’ SIM cards while here or buy her own one.