Sorry to hear of your husband's passing. Welcome to the forum.
On the matter of the welder's worth, try doing an eBay search for it, and select the option for completed listings to see the recent bids for this machine, in green if they've sold.
Hello and welcome.
Eland welders are high-quality professional machines, and this is a powerful model. Assuming it is a single-phase version ( running on normal household power via a 3-pin 13A plug ), I think it should be worth about £300.