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No need for a jigsaw. A sharp disposable saw from b&q will make the cuts you need chipboard in about 6 strokes of a saw.
Don't replicate the curve which is unlikely to match your skirting anyway. Just make a neat right angled cutout.
Edit: a steel rule taped or clamped down as a guide will help keep the cut straight if you don't care about using the saw more than a couple of times, Poundland usually have them.
£8 for whatever saw you can find and cut it in at right angles. Would take about 5 seconds. If chipping is a concern use a Stanley blade to score the line you want to cut to. Once it's in you will never look at it.