Don't know how it works INTO the UK, but FROM the UK into the EU there are three possible chargeable elements:
VAT - which UK vendors don't or shouldn't have added their end;
Admin charges (bit of a con maybe, but not huge); and
Customs charges on goods made OUTSIDE the UK shipped here FROM the UK.
As an example, my latest order of a few bits for one of mine last week:
Order value with overseas postage (Royal Mail) £114, no VAT included.
Charges on delivery here: 35€uros. Of which: French TVA at 20%, on a € value of about 134€ = 26,70€ approx. No Customs charge on UK-made goods.
Admin fee accounted for the balance.
I don't think that's too bad. Delivery is almost always under 5 working days for the things I've required, which is a day or two more than pre-Brexit maybe - but with the general deterioration in the quality of postal services in all countries, it might not be. Our post-lady used to deliver to the house Mon to Sat before 11am. Now, 3 days a week seems to be the norm, often at odd times of day.