I'm not sure what would be happening in your specific case, but as someone who in years past has organised personalised mailings during elections I can give some general information on the strategy.
Every party putting forward candidates in a constituency during a General Election period is entitled to a freepost mailing delivered through the Royal Mail. There are a couple of ways this can be done:
Unaddressed mailing - one shot only. The freepost for this category is a single delivery per dwelling.
Addressed mailings - multiple shots. The freepost facility can be used to deliver a piece of literature to every individual on the electoral register in a constituency. It's best to use this to hit a dwelling more than once. Sending the same leaflet to, for example, four adults living in the same home is a bit pointless and, given the legal maximum that a candidate is allowed to spend on their campaign, rather a waste of money.
The way we usually did it was to send one leaflet addressed to the first named on the register in the household early on, timed to land around the time the postal ballot papers were issued. Later in the campaign a second, different leaflet would be sent addressed to the second named in the household. If there was time/money a third leaflet could go to the third/fourth/etc named on the register in the household, although numbers significantly decrease by this point.
Where it can sometimes fall down with addressed mailings is in the software used. Ours (pretty technologically elderly at that point, I must admit - it has got better since, I understand) tended to treat people with different surnames as being different 'households'. So if you have an unmarried couple in one house they would be picked out as two different households so would probably both get the first mailing. This is because we had no way of knowing whether it was actually one household or a house divided into flats, for example.
Since you are named above your husband on the electoral register TheBitterBoy what might have happened is that the first mailing has gone to the second named. I would be interested to see if there is a second mailing later on, possibly at the end of this week, addressed to you. That would mean the bigger hit, which would go to every home in the constituency, lands in the run up to polling day.
The strategy will change party by party and constituency by constituency.