Hello Ken,
The link I posted (you may need to hit it twice) is a page from TNA catalogue which seems to suggest that a British member of the crew of EL LAGO was a POW who was repatriated in 1944. It could of course be a catalogue mistake. The only way to find out is to take a look at the actual document/s.
Most people who cannot easily get to the archives use one of TNAs copying service's to obtain the documents they need.
If you bring up the page (again you may need to hit it twice as it may time out)

[www.nationalarchives.gov.uk]

You will notice a REQUEST THIS button in the top right hand corner. If you hit this it will give you the options. For a document of this size I would use the Digital Express service at a cost of £8.50 for 10 pages. 24 hour service direct to your PC, no find, no fee. For larger documents it may be best to get an estimate. I must stress that both these options are copying services so you need to know exactly the pages you want and this is not always easy due to the online catalogues some times ambiguous language.

There is little or no free content which is of use to WW2 U-Boat researchers available online from TNA and apart from the "World War Two Medals issued to Merchant Seamen" which can be useful for tracking individual seamen, there are just a few pages on the interrogation of WW2 U-Boat survivors which costs £3.50 per page.

[www.nationalarchives.gov.uk]

I hope this has not confused you even more.
Best regards
Roger