Here is a partial, possible solution. I'm not sure if this will work for you or not because it depends a great deal on what else is going on in your document. This reformats footnote markers so that they conform to the requirements of the citation style.

I've used a sample bib entry from the example file provided by the package and some of the code you originally posted. I've also noted a couple of other things I think you could improve easily in terms of options you are using.

\documentclass[british]{article}
\usepackage{babel}
\usepackage[T1]{fontenc}% much better than OT1
\usepackage{mathpazo}
\usepackage[utf8]{inputenc}% much better to switch to utf8 if you can
\usepackage[style=british]{csquotes}
\usepackage[style=oscola,natbib=true]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@legislation{gorchymyn,
    title          = {Gorchymyn Mesur Teithio gan Ddysgwyr (Cymru) (Cychwyn Rhif 2)\nopunct},
    number         = {SI 2009\slash 2819},
    pagination     = {regulation},
    keywords       = {cy},
    userb          = {Cy 245},
    entrysubtype   = {secondary},
    language       = {welsh},
}% entry from oscola documentation
\end{filecontents}

\bibliography{\jobname}
\let\citet\footcite% horrible kludge

\makeatletter
  \def\@makefnmark{\hbox{\normalfont[\@thefnmark]}}% this redefines the way footnote markers are formatted. It will affect *all* footnotes - not just citations.
\makeatother

\begin{document}

THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG\citet{gorchymyn} dfdasfads

\printbibliography

\end{document}




\citet does not seem to work without a kludge (above) but \citep does.

Lyx citation problem
Because I am trying to process an immigration work permit for Canada, (I am an American citizen), I need to fly directly into Halifax from the States.  I am trying to make sure that I don't clear Canadian immigration and customs in the Philadelphia airport.  (For instance, when I fly from Toronto to the USA, I clear American immigration and customs there.)  Any ideas?
