It's actually really simple to connect; and you can probably do it for £4-£5. But there's something you need to check first...
By the look of the socketry on the TV it's either a model a few years old or something a bit bargain basement. My guess is that it's an older TV because of twin SCARTs.
Most TV sockets are one way; that is to say that they either accept signals, or they give out signals, but not both at the same time*. The notable exceptions are SCART (of which your TV has two) and a particular version of HDMI with a feature caller ARC. Your mum's TV doesn't have this because it's older than that technology.
SCART has lots of connection pins, and it was designed from the word go to be bi-directional. That's good news for you, because as long as the TV maker wired up all the pins on the inside of the TV then you can get audio out of a SCART. That's how your sound bar will connect.
What you have to do now is see if there's a user manual available online and read through to see if the SCART is wired for audio out. Chances are 19 out of 20 it is, but do what you can to be as certain as possible before laying out cash on a soundbar.
You'll need a SCART cable like this:
SCART to 6 phono. You'll only use two connections though. Depending on how the plugs are labelled it'll be either audio-in R & L or audio out R & L.
The SCART plug end goes to the TV, The phono plug ends go to the soundbar
As long as the SCART socket is fully wired then the worst case scenario is that you get sound from the TV's tuner out that socket. You might get lucky and find the TV converts audio from its AV inputs (eg HDMI for the Tivo) too, in which case then bonus!!
If Tivo is how she watches TV all the time then forget the SCART and just go optical from Tivo direct to Optical in on the sound bar. Job done.
* A 3.5mm audio jack socket is one-way by design. It has only enough physical connections to carry a stereo signal in one direction at a time.
The only way a 3.5 mm jack socket can be used either as an in or an out is by changing physical wiring connections wiring behind the socket, or by having a TV that has software controlled signal routing. . accomplished physically or by a software switch where the circuitry is built with relays to allow physical rerouting.
