I beg to differ. I made a provisional booking at our local registry office.....a year before my fiancee came over..then I had to cancel..and rebook it..twice! I did it to get written proof of our intention to marry
But let's not confuse making a provisional booking for a wedding with giving notice of marriage. For the latter both have to be present at a designated registry office. Then you say where you're going to have the wedding..be it a church...a local registry office..or some other place licence for weddings. My son got married in lulworth castle.
That is why research is key. Some people confuse the two as the same. They could also get a provisional booking from other venues.
I'm afraid not all registrar office in the UK allows you to have booking if the partner is not in the UK and yes I'm aware giving notice to marry is different thing which obviously both partners have to be present in the UK. As I said @NimLet you could ask your boyfriend he might be allowed to have the booking (he should be).