The free transfers provided with these three issues were simply sellotaped to the front covers of the comics. The first issue also included a background scene spread across the centre pages.
All the images on this page are in the SPLAT Scan Archives, but I would also like to thank Craig Spivey & Jess Harper for all their earlier contributions.
The front cover, with the transfer sheet attached:

Without the transfer sheet:

Interior page, featuring advert for next week's issue:

Centre pages background scene:
"Hi folks! How do you like your free Ewok transfers? We couldn't think of a more perfect background for them, than this Ewok village on Endor, the Ewok's home planet.
"Cut along the dotted line and then stick your background scene to card. Rub the back of your transfer evenly with a pencil or ball-point pen, and hey presto your transfer will have become part of the background scene!
"Don't forget to leave some room on your background, as there will be more Ewok transfers, free with the next two issues of Return of the Jedi, so place your order now!"
The background scene used here is a cut-down version of the background from the Thomas Salter boxed set "Ewok Village", but printed in reverse. The transfer sheets taped to the front covers of the comics use artwork taken directly from the "Ewok Village" transfer sheets.
When they said they couldn't think of a different background for the transfers, they really meant it…
The front cover, with the transfer sheet attached:

Without the transfer sheet:

Interior page, featuring advert for next week's issue:

The front cover, with the transfer sheet attached:

Without the transfer sheet:

For those of you interested in such things (that would be just me, then), the serial numbers 207 R1, 207 R2 & 207 R3 are not Letraset or Thomas Salter serials; presumably they refer to Acorn Printed Products job numbers, or are simply a convenience for the printer (Sodecor).
The film was dated 1983, & the copyright dates on the sheets reflect this, but the date of publication of these comics is April-May 1985.
Thomas Salter (who had released several "Return of the Jedi" transfer sets) were already in serious difficulties & went into receivership on the 31st December 1985 — so the re-use of this Thomas Salter artwork would very likely have fallen to Acorn Printed Products rather than Thomas Salter's "Action Transfer Products".

Picture Credit: Craig Spivey (with thanks to Jess Harper)