The chain is removed together with the sprockets. Both sprockets are press-fit to the camshaft and crankshaft, so a puller is needed to remove them. It is enough to remove only the camshaft sprocket in order to remove the chain.
I bet that the tensioner rubber pad is deeply scored after that mileage, but if it is not, and you check that all internals are OK, you can keep it. But because of the poor accessibility, it's best to replace all four items (chain, gears, tensioner), if not, you will experience rapid chain wear and noise.
I remember seeing a timing kit on Ebay, make sure that it is made for 845cc engine as 956 and 1108 will not fit.