I presume there is a spouse's death after retirement pension payable under the scheme rules and that you either have completed or will have completed 2 years' reckonable service by the time you leave service?
If so and if you are married at your date of leaving, then a similar spouse's pension (as a proportion of your preserved pension) would become payable on death after retirement. If you are not married at date of leaving, then a spouse's pension would only be payable on death after retirement if the scheme rules provide a spouse's death after retirement pension without requiring you to have been married to that particular spouse at your date of retirement (believe it or not, there are a number of schemes that include such a provision in the rules).
On death during deferment (i.e. before you reach pension age) either an immediate spouse's pension would become payable (if this is allowed for in the scheme rules) or the lump sum value of your preserved pension at your date of death would be payable into your estate.
The lump sum value would be calculated on the same basis as the transfer value you would be entitled to in lieu of your preserved pension, but would not be subject to any adjustment that might apply to transfer payments due to the scheme not satisfying the minimum funding standard.
You should check your scheme booklet to see what the provisions are relating to spouses' pensions. If it's not clear from the booklet, you are entitled under the Pensions Act disclosure regulations to see the formal scheme rules (and to take away a copy, subject to payment of a 'reasonable' fee). However, the language in which formal scheme rules are written can be hard to follow.
Of course, you could also ask the scheme administrator, but I guess you might be reluctant to ask questions that might indicate that you are thinking of leaving.