I collected all the Star Wars UK VHS releases a few years back (still own a few VHS recorders!).
The Rental Library version was released by 20th Century Fox video in 1982 and was not available for retail.
CBS/Fox then took over distribution and in 1983 released Star Wars with CBS/Fox packaging. This is the one you've most probably seen and is the first retail release of Star Wars in the UK.
To reiterate, as stated above, ESB was released in 1984 and ROTJ in 1986.
Generally the videos were released in the following packaging although there may be variations(?!) -
Star Wars Rental Library version - black box with 20th Century Fox logo on inside front cover. Pre-cert video so no certificate on cover or video. Hologram sticker on video and box side. Video cassette sticker shows 20th Century Fox logo.
Star Wars first retail version - gun metal grey box with CBS/Fox Video writing at top of box just above the inlay card and CBS/Fox logo on inside front cover. Pre-cert video so no certificate on cover or video. Video cassette sticker shows CBS/Fox logo.
ESB first release version - gun metal grey box, same as Star Wars first retail, with CBS/Fox Video writing at top of box just above the inlay card and CBS/Fox logo on inside front cover. U certificate. Video cassette has pre-printed details instead of sticker.
ROTJ first release version - white box with CBS/Fox Video writing at top of box just above the inlay card and CBS/Fox logo on inside front cover. CBX/Fox video logo and slanted text at bottom of inlay card. U certificate. Video cassette sticker shows CBS/Fox and TDK logos.
In terms of value I wouldn't (and didn't) pay more than £20 for any of these. Actually I tell a lie I did pay about £59.99 for the ESB one but that was in 1984 when it was first released!!