De acordo com a Timatic:
Visa required, except for Passengers holding confirmed onward tickets passing through United Kingdom immigration to make a landside transit to a third country on a flight that departs before 23:59 the next day. The following conditions must be complied with:
- passenger must arrive and depart by air; and
- passenger must have no purpose in entering the United Kingdom other than to pass through in transit; and
- passenger must hold all documents required for the next destination; and
- passenger must pass through United Kingdom Immigration; and
- passenger travels with a document listed in the following warning(s):
- Warning Passengers may make a landside transit if holding a valid, common format residence permit issued by an EEA Member State For details, click here or Switzerland. (SEE NOTE 57399) NOTE 57399: E-visas or e-residence permits are not accepted for landside transit.
- Warning Passengers may make a landside transit if holding a valid common format "D" visa issued by an EEA Member State For details, click here or Switzerland. (SEE NOTE 57399) NOTE 57399: E-visas or e-residence permits are not accepted for landside transit.
A partir da sua descrição, parece que você pode preencher essas restrições se você tiver a autorização de residência e o seu próximo voo sair dentro do prazo aprovado. No entanto, como você pode ver, é um conjunto complicado de restrições, portanto, confirmar com o consulado britânico que você realmente pode fazer isso seria sua melhor escolha.
Fonte: link