Well, there is good news and bad news.
The bad news is that not many of the service records for the earlier soldiers survive.
The good news is that William Lingard's seems to have survived

WO 97/625/58
WO Records created or inherited by the War Office, Armed Forces, Judge Advocate General, and related bodies
Division within WO Records of the Royal Chelsea and Kilmainham Hospitals
WO 97 Royal Hospital Chelsea: Soldiers Service Documents
Subseries within WO 97 1760-1854: discharge papers arranged by regiment, but each described at item level. (WO 97/1-1271)
WO 97/625 48th Foot: Lob - McG
Scope and content WILLIAM LINGUARD
Born KIRKHAM, Lancashire
Served in 48th Foot Regiment
Discharged aged 30
Covering dates 1806-1814
Availability Open Document, Open Description, Normal Closure before FOI Act: 30 years, This series is currently undergoing digitisation. Access to certain pieces will be disrupted over the next 3 years and advance ordering of this series is not possible during this time. Please check with us that the pieces that you wish to consult are not affected before you travel. These are microfilm records at the National Archives. They are currently being digitised for online publication on FindMyPast, but these earlier records don't go online until this time next year (April 2011).
http://www.nationalarchives.gov.uk/catalogue/displaycataloguedetails.asp?CATID=-3961119&CATLN=7&accessmethod=5You may be able to request a copy via the National Arhives website (see the "Request This" button on the above link)
William Linguard would have served in the 48th during the Peninsular Wars, but came out of the Regiment before the Battle of Waterloo took place in 1815 - The Regiment was not at Waterloo in any case. Barring illness or disciplinary issues he would have probably been at the Battle of Talavera - so he would have probably have been one of the men who earned the Regimental Battle Honour of Talavera that was worn on the Regimental Cap Badge for the next 150 years.
Steve.