Please advise on a lock and chain security combo!

Dear All

I have just invested in my first, semi-proper, adult bike. A slightly beaten-up, second-hand, Trek 7.3FX (19").

I am concerned about security whenever I leave it unattended for a few minutes (or hours!) in a city. So I before I take it anywhere, I intend to invest in a credible u-lock and chain.

Not being made of money, I have considered a medium-range combo to be potentially suitable for my needs. I should be most grateful if you more learned bicycle enthusiasts and professionals would be so kind as to advise me of whether my money would be well spent on my intended purchase, or whether I should perhaps consider a different product.

My thought so far is as follows:
- Squire Urban Protector D-Lock 2009;
- Squire 12mm Security Cable 2009 .

Would this be a good way to protect a second-hand bike, for the most reasonable sum of £27?

I look forward to reading all replies. Thank you.