Pants or loincloth beneath. In winter they would wear two or three tunics for warmth. Rich and poor alike wore the same tunic to bed as they wore during the day. Published by William Mackenzie, London. The Anglo-Saxon Chronicles.
Various versions are available, including public domain copies at archival sites.
Print copies have the added benefit of including explanatory notes and pictures of artifacts from the period. The Crystal Cave, The Hollow Hills, The Last Enchantment and The Wicked Day, all by Mary Stewart, published most recently by Coronet Books.