Hello Kenny. I see it's your first post, so firstly, welcome!
You've posted in a section that covers grading and restoration questions, so you may not get many more responses after mine. Perhaps try the section titled "Newbie Comic Collecting Questions" if you have any more.
The good news is I spotted your question, and know a little about pence books. So, let's see what we can establish to try and help you. First up, the silver age refers to 1960's books. Books dated 1974 to 1979 would be classed as 'bronze age'. Next, all first printing Marvel pence copies dated 74 to 79 would be priced between 7p and 12p. There are no pence variants (i.e. non-reprint books) priced at 35p.
So it may be that what you have are later reprints.
Best thing if you can, post some more info on titles and issue numbers etc. Pictures would be even better if you can work out how to do it. Reprints will have low value / interest to US collectors. Price variants tend to command a lower price than their cents cousins - as low as 50% unless they are key appearance books etc.
Hope this helps and good luck.