@JezBristol 

Hey

You could add something like the TL-WPA4220 and this would provide you WiFi access, however these are not always available as a single adaptor.  To be honest any of the WiFi adaptors will work for you.

It may however work out cheaper / easier for you to get a USB Network adaptor for your new laptop and just cable this in.  

@Philbert Thanks very much Phil - I've just bought an AV600... works fine then drops out :-(  Any ideas? ALso, can I use the same extender for TV (hard-wired) and WiFi at the same time. Thanks again! Jez

@JezBristol 

It could be the channel that the WiFi is broadcasting on.    That model of device is a 2.4ghz device (B/G/N) and sadly that frequency is quite flooded in nearly all scenarios.

Try logging into the WiFi adaptor by IP address and change the channel.  If you have an android phone use WiFi Analyser to see what channels are free, from experience 6 is sometimes the best of a bad bunch

Also yes, you can use cable and wifi on one plug  

@Philbert Thanks Phil - will investigate. I've also hard-wired my other laptop as that has an ethernet port, and even that keeps dropping out.  I'm wondering if there's an issue with our Virgin hub...