Does not sound to good to me. As the tappets are shimmed and not hydraulic they should be almost silent from the start. I did a engine out top end rebuild last year on my Elite 504 and hardly any tappet noise.
The bird in the hand Wreningham not far from the Lotus factory . Third Thursday of the month. from about 19.00. Keep an eye this topic as this time of year we all have things going on. I went once and was the only one there!