I can't find the plate numbers on this stamp and I can't find any information on the cancellation.
That's because it is a penny star, the design that was used from when they first went to the red color in 1841 until the new design came out (that has the plate numbers in the scroll work) in 1864. The first ones were imperforate then later they had different perforations (14 and 16), different paper types (blued and white) and a recut of the design. Yours looks to me like it's perf 14 on white paper, which came out in 1857 and lasted until they were replaced in 1864. I can't help with the cancel, it looks a bit fancy and someone could probably tell us the office it was used at. Maybe one of the London districts? The cancel covers the check letter at left so there's no way for me to tell which plate it was, you plate these by looking at characteristics of the check letters and the 'stars' in the upper corners.
