Go to an Antiques dealer for a valuation, tell the dealer its for insurance pourposes, that way your`ll get a more acurate price, than if you just asked them to buy them.
Also have you contacted Brooke Bond, there are some good antiques dealers in Maldon, or try the yellow pages and ring round, but do not at anytime say how much ae they worth, they will try and swindle you, but asking for a valuation for insurance will give you a more realistic price. Depending on how many she has, and from when the collection was started, and if she has full sets, and the condition is superb, the price could be anything from nothing up to a few hundred,,,,,, be careful though, and be sure to get at least 2 quotes, and do NOT accept an offer if the dealer wants to purchace them, what ever price is offered for cash, bear in mind they could be worth double or more than is being offered........
I hope this advise is of help to you.....