Ask about shoes, and accept the tea when it's offered
Ask "shoes off?" rather than assuming either way, accept a drink the first time it's offered (it's usually only offered once), and bring a modest gift like wine, chocolates, or flowers for a meal or party.
Ask “should I take my shoes off?” when you arrive rather than assuming, it’s a genuinely split norm here, and asking costs nothing.
Say yes the first time you’re offered a drink if you actually want one, offers aren’t always repeated, so a polite “oh, I’m fine” the first time can mean you don’t get asked again. If tea’s offered and you’d rather have coffee or water, it’s completely fine to just say so.
Bring a modest gift for a meal or party invitation, wine, a box of chocolates, or flowers all work, and a packet of biscuits is plenty for a quick tea visit. Skip the elaborate hamper, it reads as overdone rather than generous for anything short of a special occasion.
A cup of tea offered unusually late in the evening is worth a second thought — it’s sometimes a genuine offer, and sometimes a very gentle signal that it might be time to head home.
Why it matters
Unlike cultures with a firm, universal shoes-off rule, British homes split roughly down the middle, carpeted homes and homes with kids lean shoes-off, others don't mind either way, so it's a household-by-household judgment call rather than a fixed norm, worth just asking. Food and drink offers work differently here too: rather than the repeated-offer custom found in some other cultures, a British host typically offers once, so hesitating or performing a polite decline can mean you simply don't get asked again. Gifts follow a similar restraint, a small, modest gift is the right note, and something too large or elaborate can feel like it's overcorrecting for a casual visit.